<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html lang="en">
<head>
<title>Source code</title>
<link rel="stylesheet" type="text/css" href="../../../../../stylesheet.css" title="Style">
</head>
<body>
<div class="sourceContainer">
<pre><span class="sourceLineNo">001</span><a name="line.1"></a>
<span class="sourceLineNo">002</span>/*<a name="line.2"></a>
<span class="sourceLineNo">003</span> * Copyright (C) 2014 Archie L. Cobbs. All rights reserved.<a name="line.3"></a>
<span class="sourceLineNo">004</span> *<a name="line.4"></a>
<span class="sourceLineNo">005</span> * $Id: AbstractKVIterator.html 602 2015-01-05 18:49:18Z archie.cobbs $<a name="line.5"></a>
<span class="sourceLineNo">006</span> */<a name="line.6"></a>
<span class="sourceLineNo">007</span><a name="line.7"></a>
<span class="sourceLineNo">008</span>package org.jsimpledb.kv.util;<a name="line.8"></a>
<span class="sourceLineNo">009</span><a name="line.9"></a>
<span class="sourceLineNo">010</span>import java.util.Iterator;<a name="line.10"></a>
<span class="sourceLineNo">011</span><a name="line.11"></a>
<span class="sourceLineNo">012</span>import org.jsimpledb.kv.KVPair;<a name="line.12"></a>
<span class="sourceLineNo">013</span>import org.jsimpledb.kv.KVPairIterator;<a name="line.13"></a>
<span class="sourceLineNo">014</span>import org.jsimpledb.kv.KVStore;<a name="line.14"></a>
<span class="sourceLineNo">015</span>import org.jsimpledb.kv.KeyFilter;<a name="line.15"></a>
<span class="sourceLineNo">016</span>import org.jsimpledb.kv.KeyRange;<a name="line.16"></a>
<span class="sourceLineNo">017</span>import org.jsimpledb.util.ByteReader;<a name="line.17"></a>
<span class="sourceLineNo">018</span>import org.jsimpledb.util.ByteUtil;<a name="line.18"></a>
<span class="sourceLineNo">019</span>import org.slf4j.LoggerFactory;<a name="line.19"></a>
<span class="sourceLineNo">020</span><a name="line.20"></a>
<span class="sourceLineNo">021</span>/**<a name="line.21"></a>
<span class="sourceLineNo">022</span> * {@link Iterator} implementation whose values derive from key/value {@code byte[]} pairs in a {@link KVStore}.<a name="line.22"></a>
<span class="sourceLineNo">023</span> * Instances support either forward or reverse iteration.<a name="line.23"></a>
<span class="sourceLineNo">024</span> *<a name="line.24"></a>
<span class="sourceLineNo">025</span> * &lt;p&gt;&lt;b&gt;Subclass Methods&lt;/b&gt;&lt;/p&gt;<a name="line.25"></a>
<span class="sourceLineNo">026</span> *<a name="line.26"></a>
<span class="sourceLineNo">027</span> * &lt;p&gt;<a name="line.27"></a>
<span class="sourceLineNo">028</span> * Subclasses must implement {@linkplain #decodePair decodePair()} to convert key/value pairs into iteration elements.<a name="line.28"></a>
<span class="sourceLineNo">029</span> * &lt;/p&gt;<a name="line.29"></a>
<span class="sourceLineNo">030</span> *<a name="line.30"></a>
<span class="sourceLineNo">031</span> * &lt;p&gt;<a name="line.31"></a>
<span class="sourceLineNo">032</span> * This class provides a read-only implementation; for a mutable implementation, subclasses should also implement<a name="line.32"></a>
<span class="sourceLineNo">033</span> * {@link #doRemove doRemove()}.<a name="line.33"></a>
<span class="sourceLineNo">034</span> * &lt;/p&gt;<a name="line.34"></a>
<span class="sourceLineNo">035</span> *<a name="line.35"></a>
<span class="sourceLineNo">036</span> * &lt;p&gt;&lt;b&gt;Prefix Mode&lt;/b&gt;&lt;/p&gt;<a name="line.36"></a>
<span class="sourceLineNo">037</span> *<a name="line.37"></a>
<span class="sourceLineNo">038</span> * &lt;p&gt;<a name="line.38"></a>
<span class="sourceLineNo">039</span> * Instances support "prefix mode" where the {@code byte[]} keys may have arbitrary trailing garbage, which is ignored,<a name="line.39"></a>
<span class="sourceLineNo">040</span> * and so by definition no key can be a prefix of any other key. The length of the prefix is determined implicitly by the<a name="line.40"></a>
<span class="sourceLineNo">041</span> * number of key bytes consumed by {@link #decodePair decodePair()}.<a name="line.41"></a>
<span class="sourceLineNo">042</span> * When not in prefix mode, {@link #decodePair decodePair()} &lt;b&gt;must&lt;/b&gt; consume the entire key to preserve correct semantics.<a name="line.42"></a>
<span class="sourceLineNo">043</span> * &lt;/p&gt;<a name="line.43"></a>
<span class="sourceLineNo">044</span> *<a name="line.44"></a>
<span class="sourceLineNo">045</span> * &lt;p&gt;&lt;b&gt;Key Restrictions&lt;/b&gt;&lt;/p&gt;<a name="line.45"></a>
<span class="sourceLineNo">046</span> *<a name="line.46"></a>
<span class="sourceLineNo">047</span> * &lt;p&gt;<a name="line.47"></a>
<span class="sourceLineNo">048</span> * Instances are configured with an (optional) {@link KeyRange} that restricts the iteration to the specified range.<a name="line.48"></a>
<span class="sourceLineNo">049</span> * &lt;/p&gt;<a name="line.49"></a>
<span class="sourceLineNo">050</span> *<a name="line.50"></a>
<span class="sourceLineNo">051</span> * &lt;p&gt;<a name="line.51"></a>
<span class="sourceLineNo">052</span> * Instances also support filtering visible values using a {@link KeyFilter}.<a name="line.52"></a>
<span class="sourceLineNo">053</span> * To be visible in the iteration, keys must both be within the {@link KeyRange} and pass the {@link KeyFilter}.<a name="line.53"></a>
<span class="sourceLineNo">054</span> * &lt;/p&gt;<a name="line.54"></a>
<span class="sourceLineNo">055</span> *<a name="line.55"></a>
<span class="sourceLineNo">056</span> * &lt;p&gt;&lt;b&gt;Concurrent Modification&lt;/b&gt;&lt;/p&gt;<a name="line.56"></a>
<span class="sourceLineNo">057</span> *<a name="line.57"></a>
<span class="sourceLineNo">058</span> * &lt;p&gt;<a name="line.58"></a>
<span class="sourceLineNo">059</span> * Instances of this class are thread safe.<a name="line.59"></a>
<span class="sourceLineNo">060</span> * &lt;/p&gt;<a name="line.60"></a>
<span class="sourceLineNo">061</span> *<a name="line.61"></a>
<span class="sourceLineNo">062</span> * &lt;p&gt;<a name="line.62"></a>
<span class="sourceLineNo">063</span> * Internally, when not in prefix mode and no {@link KeyFilter} is configured, this instance will rely on the<a name="line.63"></a>
<span class="sourceLineNo">064</span> * iteration from {@link KVStore#getRange KVStore.getRange()}; otherwise, it will use a {@link KVPairIterator}.<a name="line.64"></a>
<span class="sourceLineNo">065</span> * Therefore, in the former case, whether this iteration always reflects the current state of the underlying<a name="line.65"></a>
<span class="sourceLineNo">066</span> * {@link KVStore} depends on the behavior of {@link KVStore#getRange KVStore.getRange()}.<a name="line.66"></a>
<span class="sourceLineNo">067</span> * &lt;/p&gt;<a name="line.67"></a>
<span class="sourceLineNo">068</span> *<a name="line.68"></a>
<span class="sourceLineNo">069</span> * @see AbstractKVNavigableMap<a name="line.69"></a>
<span class="sourceLineNo">070</span> * @see AbstractKVNavigableSet<a name="line.70"></a>
<span class="sourceLineNo">071</span> * @param &lt;E&gt; iteration element type<a name="line.71"></a>
<span class="sourceLineNo">072</span> */<a name="line.72"></a>
<span class="sourceLineNo">073</span>public abstract class AbstractKVIterator&lt;E&gt; implements java.util.Iterator&lt;E&gt; {<a name="line.73"></a>
<span class="sourceLineNo">074</span><a name="line.74"></a>
<span class="sourceLineNo">075</span>    /**<a name="line.75"></a>
<span class="sourceLineNo">076</span>     * The underlying {@link KVStore}.<a name="line.76"></a>
<span class="sourceLineNo">077</span>     */<a name="line.77"></a>
<span class="sourceLineNo">078</span>    protected final KVStore kv;<a name="line.78"></a>
<span class="sourceLineNo">079</span><a name="line.79"></a>
<span class="sourceLineNo">080</span>    /**<a name="line.80"></a>
<span class="sourceLineNo">081</span>     * Whether we are in "prefix" mode.<a name="line.81"></a>
<span class="sourceLineNo">082</span>     */<a name="line.82"></a>
<span class="sourceLineNo">083</span>    protected final boolean prefixMode;<a name="line.83"></a>
<span class="sourceLineNo">084</span><a name="line.84"></a>
<span class="sourceLineNo">085</span>    /**<a name="line.85"></a>
<span class="sourceLineNo">086</span>     * Whether this instance is iterating in the reverse direction.<a name="line.86"></a>
<span class="sourceLineNo">087</span>     */<a name="line.87"></a>
<span class="sourceLineNo">088</span>    protected final boolean reversed;<a name="line.88"></a>
<span class="sourceLineNo">089</span><a name="line.89"></a>
<span class="sourceLineNo">090</span>    // Iteration state<a name="line.90"></a>
<span class="sourceLineNo">091</span>    private final Iterator&lt;KVPair&gt; pairIterator;<a name="line.91"></a>
<span class="sourceLineNo">092</span>    private KVPair removePair;<a name="line.92"></a>
<span class="sourceLineNo">093</span>    private E removeValue;<a name="line.93"></a>
<span class="sourceLineNo">094</span><a name="line.94"></a>
<span class="sourceLineNo">095</span>// Constructors<a name="line.95"></a>
<span class="sourceLineNo">096</span><a name="line.96"></a>
<span class="sourceLineNo">097</span>    /**<a name="line.97"></a>
<span class="sourceLineNo">098</span>     * Convenience constructor for when there are no range restrictions.<a name="line.98"></a>
<span class="sourceLineNo">099</span>     *<a name="line.99"></a>
<span class="sourceLineNo">100</span>     * @param kv underlying {@link KVStore}<a name="line.100"></a>
<span class="sourceLineNo">101</span>     * @param prefixMode whether to allow keys to have trailing garbage<a name="line.101"></a>
<span class="sourceLineNo">102</span>     * @param reversed whether to iterate in the reverse direction<a name="line.102"></a>
<span class="sourceLineNo">103</span>     */<a name="line.103"></a>
<span class="sourceLineNo">104</span>    protected AbstractKVIterator(KVStore kv, boolean prefixMode, boolean reversed) {<a name="line.104"></a>
<span class="sourceLineNo">105</span>        this(kv, prefixMode, reversed, null, null);<a name="line.105"></a>
<span class="sourceLineNo">106</span>    }<a name="line.106"></a>
<span class="sourceLineNo">107</span><a name="line.107"></a>
<span class="sourceLineNo">108</span>    /**<a name="line.108"></a>
<span class="sourceLineNo">109</span>     * Convenience constructor for when the range of visible {@link KVStore} keys is all keys sharing a given {@code byte[]} prefix.<a name="line.109"></a>
<span class="sourceLineNo">110</span>     *<a name="line.110"></a>
<span class="sourceLineNo">111</span>     * @param kv underlying {@link KVStore}<a name="line.111"></a>
<span class="sourceLineNo">112</span>     * @param prefixMode whether to allow keys to have trailing garbage<a name="line.112"></a>
<span class="sourceLineNo">113</span>     * @param reversed whether to iterate in the reverse direction<a name="line.113"></a>
<span class="sourceLineNo">114</span>     * @param prefix prefix defining minimum and maximum keys<a name="line.114"></a>
<span class="sourceLineNo">115</span>     * @throws IllegalArgumentException if {@code prefix} is null or empty<a name="line.115"></a>
<span class="sourceLineNo">116</span>     */<a name="line.116"></a>
<span class="sourceLineNo">117</span>    protected AbstractKVIterator(KVStore kv, boolean prefixMode, boolean reversed, byte[] prefix) {<a name="line.117"></a>
<span class="sourceLineNo">118</span>        this(kv, prefixMode, reversed, KeyRange.forPrefix(prefix), null);<a name="line.118"></a>
<span class="sourceLineNo">119</span>    }<a name="line.119"></a>
<span class="sourceLineNo">120</span><a name="line.120"></a>
<span class="sourceLineNo">121</span>    /**<a name="line.121"></a>
<span class="sourceLineNo">122</span>     * Primary constructor.<a name="line.122"></a>
<span class="sourceLineNo">123</span>     *<a name="line.123"></a>
<span class="sourceLineNo">124</span>     * @param kv underlying {@link KVStore}<a name="line.124"></a>
<span class="sourceLineNo">125</span>     * @param prefixMode whether to allow keys to have trailing garbage<a name="line.125"></a>
<span class="sourceLineNo">126</span>     * @param reversed whether to iterate in the reverse direction<a name="line.126"></a>
<span class="sourceLineNo">127</span>     * @param keyRange key range restriction, or null for none<a name="line.127"></a>
<span class="sourceLineNo">128</span>     * @param keyFilter key filter, or null for none<a name="line.128"></a>
<span class="sourceLineNo">129</span>     * @throws IllegalArgumentException if {@code kv} is null<a name="line.129"></a>
<span class="sourceLineNo">130</span>     */<a name="line.130"></a>
<span class="sourceLineNo">131</span>    protected AbstractKVIterator(KVStore kv, boolean prefixMode, boolean reversed, KeyRange keyRange, KeyFilter keyFilter) {<a name="line.131"></a>
<span class="sourceLineNo">132</span>        if (kv == null)<a name="line.132"></a>
<span class="sourceLineNo">133</span>            throw new IllegalArgumentException("null kv");<a name="line.133"></a>
<span class="sourceLineNo">134</span>        this.kv = kv;<a name="line.134"></a>
<span class="sourceLineNo">135</span>        this.prefixMode = prefixMode;<a name="line.135"></a>
<span class="sourceLineNo">136</span>        this.reversed = reversed;<a name="line.136"></a>
<span class="sourceLineNo">137</span><a name="line.137"></a>
<span class="sourceLineNo">138</span>        // If possible use a straight KVStore iterator which is more efficient than a KVPairIterator<a name="line.138"></a>
<span class="sourceLineNo">139</span>        if (!this.prefixMode &amp;&amp; keyFilter == null) {<a name="line.139"></a>
<span class="sourceLineNo">140</span>            final byte[] minKey = keyRange != null ? keyRange.getMin() : null;<a name="line.140"></a>
<span class="sourceLineNo">141</span>            final byte[] maxKey = keyRange != null ? keyRange.getMax() : null;<a name="line.141"></a>
<span class="sourceLineNo">142</span>            this.pairIterator = this.kv.getRange(minKey, maxKey, this.reversed);<a name="line.142"></a>
<span class="sourceLineNo">143</span>        } else<a name="line.143"></a>
<span class="sourceLineNo">144</span>            this.pairIterator = new KVPairIterator(this.kv, keyRange, keyFilter, this.reversed);<a name="line.144"></a>
<span class="sourceLineNo">145</span>    }<a name="line.145"></a>
<span class="sourceLineNo">146</span><a name="line.146"></a>
<span class="sourceLineNo">147</span>// Iterator<a name="line.147"></a>
<span class="sourceLineNo">148</span><a name="line.148"></a>
<span class="sourceLineNo">149</span>    @Override<a name="line.149"></a>
<span class="sourceLineNo">150</span>    public boolean hasNext() {<a name="line.150"></a>
<span class="sourceLineNo">151</span>        return this.pairIterator.hasNext();<a name="line.151"></a>
<span class="sourceLineNo">152</span>    }<a name="line.152"></a>
<span class="sourceLineNo">153</span><a name="line.153"></a>
<span class="sourceLineNo">154</span>    @Override<a name="line.154"></a>
<span class="sourceLineNo">155</span>    public synchronized E next() {<a name="line.155"></a>
<span class="sourceLineNo">156</span><a name="line.156"></a>
<span class="sourceLineNo">157</span>        // Get next key/value pair<a name="line.157"></a>
<span class="sourceLineNo">158</span>        final KVPair pair = this.pairIterator.next();<a name="line.158"></a>
<span class="sourceLineNo">159</span><a name="line.159"></a>
<span class="sourceLineNo">160</span>        // Decode key/value pair<a name="line.160"></a>
<span class="sourceLineNo">161</span>        final ByteReader keyReader = new ByteReader(pair.getKey());<a name="line.161"></a>
<span class="sourceLineNo">162</span>        final E value = this.decodePair(pair, keyReader);<a name="line.162"></a>
<span class="sourceLineNo">163</span>        if (!this.prefixMode &amp;&amp; keyReader.remain() &gt; 0) {<a name="line.163"></a>
<span class="sourceLineNo">164</span>            LoggerFactory.getLogger(this.getClass()).error(this.getClass().getName() + "@"<a name="line.164"></a>
<span class="sourceLineNo">165</span>              + Integer.toHexString(System.identityHashCode(this)) + ": " + keyReader.remain() + " undecoded bytes remain in key "<a name="line.165"></a>
<span class="sourceLineNo">166</span>              + ByteUtil.toString(pair.getKey()) + ", value " + ByteUtil.toString(pair.getValue()) + " -&gt; " + value);<a name="line.166"></a>
<span class="sourceLineNo">167</span>        }<a name="line.167"></a>
<span class="sourceLineNo">168</span><a name="line.168"></a>
<span class="sourceLineNo">169</span>        // In prefix mode, skip over any additional keys having the same prefix as what we just decoded<a name="line.169"></a>
<span class="sourceLineNo">170</span>        if (this.prefixMode) {<a name="line.170"></a>
<span class="sourceLineNo">171</span>            final KVPairIterator kvPairIterator = (KVPairIterator)this.pairIterator;<a name="line.171"></a>
<span class="sourceLineNo">172</span>            final byte[] prefix = keyReader.getBytes(0, keyReader.getOffset());<a name="line.172"></a>
<span class="sourceLineNo">173</span>            kvPairIterator.setNextTarget(this.reversed ? prefix : ByteUtil.getKeyAfterPrefix(prefix));<a name="line.173"></a>
<span class="sourceLineNo">174</span>        }<a name="line.174"></a>
<span class="sourceLineNo">175</span><a name="line.175"></a>
<span class="sourceLineNo">176</span>        // Done<a name="line.176"></a>
<span class="sourceLineNo">177</span>        this.removePair = pair;<a name="line.177"></a>
<span class="sourceLineNo">178</span>        this.removeValue = value;<a name="line.178"></a>
<span class="sourceLineNo">179</span>        return value;<a name="line.179"></a>
<span class="sourceLineNo">180</span>    }<a name="line.180"></a>
<span class="sourceLineNo">181</span><a name="line.181"></a>
<span class="sourceLineNo">182</span>    @Override<a name="line.182"></a>
<span class="sourceLineNo">183</span>    public void remove() {<a name="line.183"></a>
<span class="sourceLineNo">184</span>        final E removeValueCopy;<a name="line.184"></a>
<span class="sourceLineNo">185</span>        final KVPair removePairCopy;<a name="line.185"></a>
<span class="sourceLineNo">186</span>        synchronized (this) {<a name="line.186"></a>
<span class="sourceLineNo">187</span>            if ((removePairCopy = this.removePair) == null)<a name="line.187"></a>
<span class="sourceLineNo">188</span>                throw new IllegalStateException();<a name="line.188"></a>
<span class="sourceLineNo">189</span>            this.removePair = null;<a name="line.189"></a>
<span class="sourceLineNo">190</span>            removeValueCopy = this.removeValue;<a name="line.190"></a>
<span class="sourceLineNo">191</span>        }<a name="line.191"></a>
<span class="sourceLineNo">192</span>        this.doRemove(removeValueCopy, removePairCopy);<a name="line.192"></a>
<span class="sourceLineNo">193</span>    }<a name="line.193"></a>
<span class="sourceLineNo">194</span><a name="line.194"></a>
<span class="sourceLineNo">195</span>// Subclass methods<a name="line.195"></a>
<span class="sourceLineNo">196</span><a name="line.196"></a>
<span class="sourceLineNo">197</span>    /**<a name="line.197"></a>
<span class="sourceLineNo">198</span>     * Decode an iteration element from a key/value pair.<a name="line.198"></a>
<span class="sourceLineNo">199</span>     *<a name="line.199"></a>
<span class="sourceLineNo">200</span>     * &lt;p&gt;<a name="line.200"></a>
<span class="sourceLineNo">201</span>     * If not in prefix mode, all of {@code keyReader} must be consumed; otherwise, the consumed portion<a name="line.201"></a>
<span class="sourceLineNo">202</span>     * is the prefix and any following keys with the same prefix are ignored.<a name="line.202"></a>
<span class="sourceLineNo">203</span>     * &lt;/p&gt;<a name="line.203"></a>
<span class="sourceLineNo">204</span>     *<a name="line.204"></a>
<span class="sourceLineNo">205</span>     * @param pair key/value pair<a name="line.205"></a>
<span class="sourceLineNo">206</span>     * @param keyReader key input<a name="line.206"></a>
<span class="sourceLineNo">207</span>     * @return decoded iteration element<a name="line.207"></a>
<span class="sourceLineNo">208</span>     */<a name="line.208"></a>
<span class="sourceLineNo">209</span>    protected abstract E decodePair(KVPair pair, ByteReader keyReader);<a name="line.209"></a>
<span class="sourceLineNo">210</span><a name="line.210"></a>
<span class="sourceLineNo">211</span>    /**<a name="line.211"></a>
<span class="sourceLineNo">212</span>     * Remove the previously iterated value.<a name="line.212"></a>
<span class="sourceLineNo">213</span>     *<a name="line.213"></a>
<span class="sourceLineNo">214</span>     * &lt;p&gt;<a name="line.214"></a>
<span class="sourceLineNo">215</span>     * The implementation in {@link AbstractKVIterator} always throws {@link UnsupportedOperationException}.<a name="line.215"></a>
<span class="sourceLineNo">216</span>     * Subclasses should override to make the iterator mutable.<a name="line.216"></a>
<span class="sourceLineNo">217</span>     * &lt;/p&gt;<a name="line.217"></a>
<span class="sourceLineNo">218</span>     *<a name="line.218"></a>
<span class="sourceLineNo">219</span>     * @param value most recent value returned by {@link #next}<a name="line.219"></a>
<span class="sourceLineNo">220</span>     * @param pair the key/value pair corresponding to {@code value}<a name="line.220"></a>
<span class="sourceLineNo">221</span>     */<a name="line.221"></a>
<span class="sourceLineNo">222</span>    protected void doRemove(E value, KVPair pair) {<a name="line.222"></a>
<span class="sourceLineNo">223</span>        throw new UnsupportedOperationException();<a name="line.223"></a>
<span class="sourceLineNo">224</span>    }<a name="line.224"></a>
<span class="sourceLineNo">225</span>}<a name="line.225"></a>
<span class="sourceLineNo">226</span><a name="line.226"></a>




























































</pre>
</div>
</body>
</html>
